What does blue mean on a tree?

Jill Davis/US Army Corps of Engineers

Timber marking symbols using paint and other tree scribing methods are not universally accepted in North American forests. There is no national code that mandates the use of painted slashes, dots, circles and X's. There is no color used as a code that is more than a regional preference and usually accepted only locally. Even the United States Forest Service uses different marks and colors depending on the national forest and/or national forest region.

However, there are many reasons to mark trees and forest timber. Trees may be marked to indicate a tree to be cut or left as per the forest management plan. Trees on forest boundary lines can be marked to indicate property ownership. Trees inside large forests can be permanently marked as part of a forest inventory system.

Forest Tree Marking Meanings

There are no national tree marking standards even if many of them are similar.

Forestry organizations have tried for years to set a few guidelines for tree and timber marks. But foresters are an independent breed and many see their tree marking designs and system as their personal or company imprint or brand. Circles, number of slashes and other quick paint spurts, including stump marks, usually signifies cutting status along with the quality or grade of the tree marked. Boundary line colors often designate land belonging to a particular owner and usually painted over some removed bark (scars) to last longer.

Marks Used in Selecting a Tree to Cut

Selecting trees to cut is the most common mark made, often done using paint. Unmarked trees that are left usually have the best potential to make the most productive future second crop. The paint color is usually blue on trees to be cut and the tree's intended product is identified by different paint slashes and symbols. Again, you are actually selecting the best trees with potential value by not marking them.

There is a system described in the Wisconsin DNR Silviculture Handbook on trees to be marked that ensure the production of high-quality sawtimber products. The selection of trees to cut should apply the following order of removal to achieve the desired residual stand composition and structure. Nel-spot Paint Company manufactures the most popular paints used by the forest industry and their very popular blue is the most often used paint used to denote a tree to be used.

6 Reasons to Mark a Tree for Removal

1. High risk of mortality or failure (unless retained as a wildlife tree)
2. Poor stem form and quality
3. Less desirable species
4. Release of future crop trees
5. Low crown vigor
6. Improve spacing

This order of removal will vary with landowner goals, the stand management plan, and silvicultural treatment. Examples would be a shelterwood seed cut that would open the forest floor to tree regeneration or the permanent removal of exotic invasive species. Removal of undesirable species would preserve the quality of an expected new stand.

Marks Used for Boundary Lines

Maintaining forest boundary lines is one major duty of the forest manager and tree marking is a part of that. Most forest landowners generally know where their boundary lines are and have accurately surveyed maps and photography but very few have their lines marked clearly on the ground.

A clearly marked boundary is the best evidence that you know where your landlines are. Marked boundaries minimize the risk of problems, such as timber trespass, caused by others making inaccurate assumptions about your boundaries. They also help you avoid trespassing on your neighbors’ land when you cut trees or build roads and trails.

Colored plastic ribbon or “flagging” is often used as a temporary location of boundary lines but should be followed by more permanent blazing and/or painting trees along and near the line. Make sure you are using the latest recorded survey.

5 Steps to Mark Your Forest Boundary

1. Contacting your boundary neighbor is courtesy at its best as new line claims can cause disagreements.
2. An axed blaze 5-6” long and 3-4” wide at 4 to 5 feet above the ground should be made. Limit the cut to just enough bark and outer wood to make it visible. Avoid blazing over old blazes as they become supporting evidence of the original location of the line.
3. Paint both the blazed surface including 1-2” of bark (to over-paint forming callous tissue). Use a bright (fluorescent blue, red, or orange seem to work best) durable brush-on paint. Nel-spot makes great boundary paint.
4. Many timber company forest owners blaze side trees on the line side it faces. This exactness can be helpful but takes a recent survey line for exactness.
5. Mark trees close enough so that from any mark you can see the next mark in either direction.